Note: Descriptions are shown in the official language in which they were submitted.
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ADJUSTMENT OF A TRAFFIC SIGNAL CONTROL PLAN BASED ON LOCAL
ENVIRONMENTAL CONDITIONS
BACKGROUND
[0001] The present invention relates generally to traffic management system
and
more specifically to, adjustment of a traffic signal control plan based on
local
environmental conditions.
[0002] In general, traffic management systems are utilized to control the
operation of traffic signals along arterial roads. The goal of the traffic
management
system is to maximize vehicle throughput on the arterial road while minimizing
delays.
Traffic signal controllers are used to control the operation of traffic
signals along the
arterial roads and to adjust the signal phasing and timing based on the time
and day of the
week. The traffic signal controller operates a traffic signal based on a
signal control plan
that dictates the signal phasing and timing.
[0003] While existing traffic management systems adjust signal phasing and
timing based on the time and day of the week, these are not the only factors
that affect
traffic patterns and driver behaviors. One factor that has a large impact on
traffic patterns
and driver behaviors is the weather. However, existing traffic management
systems are
not designed to take into account the weather when adjusting signal phasing
and timing.
SUMMARY
[0004] According to one embodiment, a method for adjusting a signal control
plan for a traffic signal at an intersection based on local environmental
conditions is
provided. The method includes operating the traffic signal based on a standard
signal
control plan, receiving an indication of an adverse environmental condition,
and
determining if the standard signal control plan should be adjusted based on
the indication
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of the adverse environmental condition. Based on determining that the standard
signal control
plan should be adjusted based on the indication of the adverse environmental
condition, the
method includes creating a modified signal control plan based on the adverse
environmental
condition and the standard signal control plan and operating the traffic
signal based on the
modified signal control plan.
[0005] According to another embodiment, a traffic signal controller
having a
processor that is configured to operate a traffic signal by preforming a
method is provided.
The method includes operating the traffic signal based on a standard signal
control plan,
receiving an indication of an adverse environmental condition, and determining
if the standard
signal control plan should be adjusted based on the indication of the adverse
environmental
condition. Based on determining that the standard signal control plan should
be adjusted based
on the indication of the adverse environmental condition, the method includes
creating a
modified signal control plan based on the adverse environmental condition and
the standard
signal control plan and operating the traffic signal based on the modified
signal control plan.
[0006] According to yet another embodiment, roadside equipment for
operating a
traffic signal at an intersection includes a traffic signal controller that
operates a traffic signal
for the intersection. The traffic signal controller performs a method
including receiving an
indication of an abnormal condition of a road in a vicinity of the
intersection, storing the
abnormal condition in a memory of the roadside equipment, and broadcast a
warning message
notifying connected devices in the vicinity of the intersection of the
abnormal condition based
on a type of the abnormal condition.
[0006a] According to another aspect of the present invention, there is
provided a
method for adjusting a signal control plan for a traffic signal at an
intersection based on local
environmental conditions, the method comprising: operating the traffic signal
based on a
standard signal control plan; receiving an indication of an adverse
environmental condition;
determining if the standard signal control plan should be adjusted based on
the indication of
the adverse environmental condition; based on determining that the standard
signal control
plan should be adjusted based on the indication of the adverse environmental
condition,
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creating a modified signal control plan based on the adverse environmental
condition and the
standard signal control plan; operating the traffic signal based on the
modified signal control
plan by changing a length of at least one of a yellow light time and a green
light time within a
length of a phase that includes at least three sub-phases that correspond to a
red light time and
the yellow light time and the green light time; determining whether the
adverse environmental
condition concluded; based on determining that the adverse environmental
condition
concluded, operating the traffic signal based on the standard signal control
plan; and based on
determining that the adverse environmental condition has not concluded,
operating the traffic
signal based on the modified signal control plan wherein the indication of the
adverse
environmental condition is received from a sensor connected to roadside
equipment disposed
at the intersection; and wherein the determination of whether the signal
control plan should be
adjusted based on the adverse environmental condition is based on one or more
of: a severity
of the adverse environmental condition; a location of the adverse
environmental condition; a
number of indications received of for the adverse environmental condition; and
a source of the
indication of an adverse environmental condition.
10006b1
According to another aspect of the present invention, there is provided a
traffic
signal controller comprising: a processor configured to operate a traffic
signal, the processor
configured to perform a method comprising: receiving a standard signal control
plan;
operating the traffic signal based on the standard signal control plan;
receiving an indication
of an adverse environmental condition; determining if the standard signal
control plan should
be adjusted based on the indication of the adverse environmental condition;
based on
determining that the standard signal control plan should be adjusted based on
the indication of
the adverse environmental condition, creating a modified signal control plan
based on the
adverse environmental condition and the standard signal control plan;
operating the traffic
signal based on the modified signal control plan by changing a length of at
least one of a
yellow light time and a green light time within a length of a phase that
includes at least three
sub-phases that correspond to a red light time and the yellow light time and
the green light
time; determining whether the adverse environmental condition concluded; based
on
determining that the adverse environmental condition concluded, operating the
traffic signal
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based on the standard signal control plan; and based on determining that the
adverse
environmental condition has not concluded, operating the traffic signal based
on the modified
signal control plan; wherein the indication of the adverse environmental
condition is received
from a sensor connected to roadside equipment disposed at the intersection,
and wherein the
determination of whether the signal control plan should be adjusted based on
the adverse
environmental condition is based on one or more of: the severity of the
adverse environmental
condition; the location of the adverse environmental condition; a number of
indications
received of for the adverse environmental condition; and the source of the
indication of an
adverse environmental condition.
[0007]
Additional features and advantages are realized through the techniques of the
present invention. Other embodiments and aspects of the invention are
described in detail
herein and are considered a part of the claimed invention. For a better
understanding of the
invention with the advantages and the features, refer to the description and
to the drawings.
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BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0008] The subject matter which is regarded as the invention is
particularly
pointed out and distinctly claimed in the claims at the conclusion of the
specification.
The forgoing and other features, and advantages of the invention are apparent
from the
following detailed description taken in conjunction with the accompanying
drawings in
which:
[0009] FIG. 1 is a schematic diagram illustrating an intersection in
accordance
with an exemplary embodiment;
[0010] FIG. 2 is a block diagram illustrating a cycle of a signal control
plan for an
intersection in accordance with an exemplary embodiment;
[0011] FIG. 3 is a block diagram of roadside equipment in accordance with
an
exemplary embodiment;
[0012] FIG. 4 is a block diagram of database used to store information
relating to
an intersection in accordance with an exemplary embodiment; and
[0013] FIG. 5 is a flow chart diagram illustrating a method for adjusting a
signal
control plan based on local environmental conditions in accordance with an
exemplary
embodiment.
DETAILED DESCRIPTION
[0014] Exemplary embodiments include methods, systems and computer program
products for adjusting a signal control plan of a traffic signal based on
local
environmental conditions. In exemplary embodiments, roadside equipment
configured to
operate a traffic signal for an intersection receives an indication of an
adverse
environmental condition in the area of the intersection and responsively
adjusts the signal
control plan of the traffic signal. For example, in response to receiving an
indication that
it is raining in the area of the intersection the roadside equipment may
adjust the signal
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control plan to increase a yellow light time to give drivers additional time
to stop and/or
clear the intersection. In another example, in response to receiving an
indication that
there is a weather event which requires evacuation in the area of the
intersection the
roadside equipment may increase the length of the green light time of the
signal control
plan along an evacuation route to increase the number of travelers that can
evacuate. In
exemplary embodiments, the roadside equipment includes a memory that stores
the
received indications of an adverse environmental condition in addition to
other
information regarding the intersection.
[0015] Referring now to FIG. 1, a block diagram of an intersection 100 in
accordance with an exemplary embodiment is shown. As illustrated, the
intersection 100
of a main street 102 and a side street 104 includes a traffic signal 106 that
is configured to
control the flow of vehicles 112 through the intersection 100. In exemplary
embodiments, the traffic signal 106 is controlled by a traffic signal
controller 108, which
is part of roadside equipment 114. In exemplary embodiments, the roadside
equipment
114 is in communication with a traffic management system 110 and the vehicles
112 may
be configured communicate with the roadside equipment 114 via wireless
communication
devices. In exemplary embodiments, the traffic management system 110 may be
connected to the roadside equipment 114 by a fiber optic cable, copper wire,
or by other
suitable means. In exemplary embodiments, the traffic signal controller 108
may receive
signal control plans from the traffic management system 110 which are used to
govern
the operation of the traffic signal 106 during different times of the day and
days of the
week.
[0016] Referring now to FIG. 2, a block diagram of a cycle 200 of a signal
control plan in accordance with an exemplary embodiment is shown. As
illustrated, the
cycle 200 includes four phases of operation 210, 220, 230, 240. For example,
the cycle
200 may include a first phase 210 that corresponds to a main street left turn
traffic
condition, a second phase 220 that corresponds to a main street through
condition, a third
phase 230 that corresponds to a side street left turn traffic condition, and a
fourth phase
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240 that corresponds to a side street through condition. As illustrated, the
first phase 210,
and the cycle 200, starts at time To, the second phase 220 starts at time T1,
the third phase
230 starts at time T2, the fourth phase 240 starts at time T3, the fourth
phase 220, and the
cycle 200, ends at time T4 Accordingly, the period of the cycle, or cycle
length, is
defined as T4-T0.
[0017] Each phase 210, 220, 230, 240 includes three sub-phases that
correspond
to green light time 212, 222, 232, 242, yellow light time 214, 224, 234, 244,
and red light
time 216, 226, 236, 246. Although, the length of each phase 210, 220, 230, 240
is shown
as approximately equal, it will be understood by those of ordinary skill in
the art that the
length of each phase 210, 220, 230, 240 may be different. Likewise, even
though the
green light time 212, 222, 232, 242 of each phase 210, 220, 230, 240 is shown
as
approximately equal, it will be understood by those of ordinary skill in the
art that the
green light time 212, 222, 232, 242 of each phase 210, 220, 230, 240 may be
different.
[0018] In exemplary embodiments, a standard signal control plan received by
the
traffic signal controller includes a cycle for the traffic signal that is
continually repeated.
In exemplary embodiments, the traffic signal controller is configured to
employ different
standard signal control plans during different times of the day and on
different days of the
week. For example, during morning rush hour it may be desirable for a longer
portion of
the cycle to be devoted to one phase of the cycle than during lunch time.
Accordingly,
the traffic signal controller may be configured to switch between standard
signal control
plans multiple times during the day. In exemplary embodiments, the traffic
signal
controller is configured to selectively modify the standard signal control
plan that is
currently being executed based on receiving an indication of an adverse
environmental
condition in the area of the intersection.
[0019] Referring now to FIG. 3, a block diagram of roadside equipment 300
in
accordance with an exemplary embodiment is shown. As illustrated, the roadside
equipment 300 includes a network interface 302, a traffic signal controller
304, a memory
306, a battery 308, a power source 310, a transceiver 312, and an antenna 314.
In one
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embodiment, the network interface 302 is configured to connect the roadside
equipment
300 to a traffic management system via an Ethernet cable. The roadside
equipment 300 is
configured to receive information from the traffic management system and to
use the
traffic signal controller 304 and the memory 306 to process and store the
received
information.
[0020] In exemplary embodiments, the memory 306 may include any of a wide
variety of memory devices including volatile and non-volatile memory devices.
The
memory 306 may be used to store signal plans received from the traffic
management
system and to store additional information relating to the intersection. In
exemplary
embodiments, the additional information relating to the intersection may be
received
from connected devices. As used herein, the term connected devices refers to
any device
which has the necessary wireless communications equipment to send and/or
receive
messages from roadside equipment 300. Likewise, the term connected vehicle
refers to a
vehicle which has the necessary wireless communications equipment to send
and/or
receive messages from roadside equipment 300.
[0021] In exemplary embodiments, the network interface 302 may be
configured
to receive information from the Internet either directly or indirectly via the
traffic
management system. For example, the traffic management system may be
configured to
monitor weather conditions and to selectively send messages to roadside
equipment 300
that indicate an adverse environmental condition in the geographic area of the
roadside
equipment 300. In exemplary embodiments, the network interface 302 may be
configured to communicate with a web service that uses social media or other
sources to
gather information regarding the weather conditions or road conditions in the
geographic
area of the roadside equipment 300.
[0022] In exemplary embodiments, the roadside equipment 300 may include
one
or more sensors 316 that are configured to monitor the local environmental
conditions
around the roadside equipment 300. In exemplary embodiments, the sensors 316
may
include, but are not limited to, a thermometer, a barometer, an anemometer, a
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hygrometer, wind vanes, video cameras, or the like. The traffic signal
controller 304
monitors the output of the sensors 316 to determine the presence of an adverse
environmental condition In exemplary embodiments, the local environmental
conditions
may include but are not limited to, rain, snow, ice, fog or the like.
[0023] In exemplary embodiments, the roadside equipment 300 is configured
to
receive power from power source 310 and to charge a battery 308. The battery
308 is
configured to provide power to the roadside equipment 300 in the event of an
interruption
or failure of the power source 310. In exemplary embodiments, the power source
310
may be a power over Ethernet power source and the network interface 302 may be
configured to receive both data and power over an Ethernet connection. In
exemplary
embodiments, the battery 308 may be a lead acid battery, a lithium ion
battery, a nickel
cadmium battery or the like.
[0024] In exemplary embodiments, the roadside equipment 300 includes
multiple
transceivers 312 and antennas 314 which are each configured to communicate on
different communications channels, or frequencies. In other embodiments, the
roadside
equipment 300 may be configured to use a single antenna 314 and transceiver
312 to
communicate over a range of communications channels, or frequencies. In
exemplary
embodiments, the transceivers 312 and antennas 314 of the roadside equipment
300 are
configured to communicate with connected vehicles and other connected devices
within
range of the roadside equipment 300. For example, the transceivers 312 may
include a
5.9 GHz short range wireless communications device that is capable of both
sending and
receiving messages from nearby connected vehicles.
[0025] In one embodiment, vehicles may be configured to detect adverse
environmental conditions, such as rain, ice or snow on the road, or the like
through the
use of one or more known sensors on the vehicle. For example, a vehicle may
detect that
the road is wet or icy based on the activation of its ABS. Upon detecting such
an adverse
environmental condition, the vehicle may periodically or continuously
broadcast a short
range message indicating the detected adverse environmental condition. In
exemplary
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embodiments, such messages may be received by the roadside equipment 300 and
by
other connected devices that are within range of the vehicle.
[0026] In exemplary embodiments, the roadside equipment 300 may store
these
messages in the memory 306 and may re-broadcast these messages to other
connected
devices that are within range of the roadside equipment 300. In one
embodiment, as the
messages are received the adverse environmental condition reported may be
stored in a
database in the memory 306 with a timestamp indicating when the message
reporting the
adverse environmental condition was received. The roadside equipment 300 may
be
configured to broadcast a message warning of the reported adverse
environmental
condition for a predetermined period of time from the timestamp. In exemplary
embodiments, if multiple messages are received indicating the same adverse
environmental condition, the timestamp for the adverse environmental condition
will be
updated with the most recent time at which a message was received.
[0027] Referring now to FIG. 4, a block diagram of database 400 used to
store
information relating to an intersection in accordance with an exemplary
embodiment is
shown. The information relating to the intersection may include, but is not
limited to, an
environmental condition in the area of the intersection, a condition of the
road, or any
other abnormal condition relating to the intersection. In exemplary
embodiments, the
database 400 is stored in the memory of a roadside equipment for an
intersection and
stores a plurality of records 420 that each correspond to a condition of the
intersection.
In exemplary embodiments, each of the records 420 can include a condition type
402, a
source 404, a timestamp 406, a rebroadcast flag 408, a duplicate flag 410, and
a counter
412. In exemplary embodiments, the condition type 402 field is used to store
the
reported condition of the road at the intersection and may include, but is not
limited to,
wet, ice, pot hole, or the like. In exemplary embodiments, the source 404
filed is used to
store the source of the reported condition type 402 of the road at the
intersection and may
include, but is not limited to, a connected vehicle (CV), a sensor, the
interne, or the like.
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In exemplary embodiments, the timestamp 406 filed is used to store the most
recent time
that the condition type 402 of the road at the intersection was reported.
[0028] In exemplary embodiments, the roadside equipment may broadcast a
warning message to notify connected devices in the area of the intersection of
the
condition type 402. The rebroadcast flag 406 is used to store a flag that
indicates if the
roadside equipment will broadcast the warning message. In exemplary
embodiments,
the determination of whether the roadside equipment will broadcast a warning
message
for the condition is based on the type the condition type 402. For example,
the roadside
equipment may broadcast warning messages relating to icy conditions but may
not
broadcast warning messages relating to pot holes. In other embodiments, the
roadside
equipment may transmit a notification of the condition to a traffic management
system
based on the condition type 402. For example, the roadside equipment may
transmit a
notification to a traffic management system relating to pot holes but may not
transmit a
notification relating to icy conditions.
[0029] In exemplary embodiments, the duplicate flag 410 is used to store a
flag
that indicates if the condition type 402 has been reported more than once. The
counter
412 field is used to store the number of times the condition has been reported
if the
duplicate flag 410 indicates that the condition has been reported more than
once. In
exemplary embodiments, the determination of whether the roadside equipment
will
broadcast a warning message for the condition type 402 may also be based on
the source
and number of times that a condition type 402 has been reported.
[0030] Those of skill in the art will recognize that not all details are
shown in the
simplified block diagram shown in FIG. 3. In exemplary embodiments, the
antenna 314
may be dedicated to a single transceiver 312, or may be connected to be shared
with other
components. The traffic signal controller 304 may be configured to perform
only the
processes described herein, or can also be configured to perform other
processes for the
operation and management the roadside equipment 300. The various components of
FIG.
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3 could be constructed as separate elements connected to communicate with each
other or
two or more of these components could be integrated into a single device.
[0031] Referring now to FIG. 5, a flow chart diagram illustrating a method
500
for adjusting a signal control plan based on local environmental conditions in
accordance
with an exemplary embodiment is shown. As shown at block 502, the method 500
includes operating a traffic signal based on a standard signal control plan.
Next, as
shown at block 504, the method includes receiving an indication of an adverse
environmental condition in the area of the traffic signal. In exemplary
embodiments, the
indication of the adverse environmental condition may be received from a
sensor of the
roadside equipment, from a vehicle in proximity to the roadside equipment,
from the
Internet, or from any other of a variety of sources. In exemplary embodiments,
the
adverse environmental condition may include, but is not limited to, rain, fog,
snow or ice
in the area of the traffic signal.
[0032] As shown at decision block 506 the method 500 includes determining
if
the signal control plan should be adjusted based on the indication of the
adverse
environmental condition. In exemplary embodiments, the determination of
whether the
signal control plan should be adjusted based on the adverse environmental
condition may
be based one or more of: on the severity of the adverse environmental
condition; the
location of the adverse environmental condition; the number of indications
received of
the adverse environmental condition; and the source of the indication of an
adverse
environmental condition. For example, if the adverse environmental condition
is
detected by a sensor connected the roadside equipment the signal control plan
may be
immediately adjusted. In another example, if the notification of the adverse
environmental condition is received from a weather alert service via the
Internet, the
roadside equipment may be configured to wait for a local sensor or vehicle to
report the
adverse environmental condition.
[0033] Continuing with reference to FiG. 5, if the signal control plan
should not
be adjusted based on the indication of the adverse environmental condition,
the method
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500 proceeds to block 502 and operates the traffic signal based on the
standard signal
control plan. Otherwise, the method 500 proceeds to block 510 and creates a
modified
signal control plan based on the adverse environmental condition and the
standard signal
control plan. Next, as shown at block 512 the method 500 includes operating
the traffic
signal based on the modified signal control plan. As shown at decision block
514, the
method 500 includes determining if the adverse environmental condition
concluded. If
the adverse environmental condition has concluded, the method 500 returns to
block 502
and operates the traffic signal based on the standard signal control plan. If
the adverse
environmental condition has not concluded, the method 500 returns to block 512
and
operates the traffic signal based on the modified signal control plan.
[0034] In one embodiment, the determination of whether the adverse
environmental condition has concluded may be based on a predetermined period
of time
= elapsing since the last indication of adverse environmental condition was
received. In
another embodiment, the determination of whether the adverse environmental
condition
has concluded may be based on receiving a reading from a sensor that indicates
that the
environmental condition in the area of the traffic signal has returned to
normal. In yet
another embodiment, the determination of whether the adverse environmental
condition
has concluded may be based upon the expiration of severe weather advisory or
warning.
[0035] In one embodiment if the adverse environmental condition in
the area of
the intersection is ice or snow on the road, rain or heavy fog, the signal
control plan may
be adjusted to increase the length of yellow light times. By increase the
length of yellow
light times the chance of accidents from cars sliding into the intersection
can be reduced.
In another embodiment if the adverse environmental condition is a weather
event which
requires evacuation, such as a hurricane, the signal control plan may be
adjusted to
increase the length of the green light time along an evacuation route to
increase the
number of travelers that can evacuate.
[0036] The terminology used herein is for the purpose of
describing particular
embodiments only and is not intended to be limiting of the invention. As used
herein, the
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singular forms "a", "an" and "the" are intended to include the plural forms as
well, unless
the context clearly indicates otherwise. It will be further understood that
the terms
"comprises" and/or "comprising," when used in this specification, specify the
presence of
stated features, integers, steps, operations, elements, and/or components, but
do not
preclude the presence or addition of one or more other features, integers,
steps,
operations, element components, and/or groups thereof.
[0037] The corresponding structures, materials, acts, and equivalents of
all means
or step plus function elements in the claims below are intended to include any
structure,
material, or act for performing the function in combination with other claimed
elements
as specifically claimed. The description of the present invention has been
presented for
purposes of illustration and description, but is not intended to be exhaustive
or limited to
the invention in the form disclosed. Many modifications and variations will be
apparent
to those of ordinary skill in the art without departing from the scope and
spirit of the
invention. The embodiment was chosen and described in order to best explain
the
principles of the invention and the practical application, and to enable
others of ordinary
skill in the art to understand the invention for various embodiments with
various
modifications as are suited to the particular use contemplated.
[0038] The flow diagrams depicted herein are just one example. There may be
many variations to this diagram or the steps (or operations) described therein
without
departing from the spirit of the invention. For instance, the steps may be
performed in a
differing order or steps may be added, deleted or modified. All of these
variations are
considered a part of the claimed invention.
[0039] While the preferred embodiment to the invention had been described,
it
will be understood that those skilled in the art, both now and in the future,
may make
various improvements and enhancements which fall within the scope of the
claims which
follow. These claims should be construed to maintain the proper protection for
the
invention first described.
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